Method of controlling alternating-current motors.



PATENTBD JUNE 23, 1903.

L L U A R I G M T u 7 8 N L 3 7 0 N METHOD 0E CONTROLLING ALTERNATINGCURRENT MOTORS.

APPLIOATION I'ILED APR. 26, 1901.

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6224M AM vnorouwfna. WASNINGTON o c BAEf-KENTED JUNE 23, .1903.

PI J I. METHOD OF CONTROLLING ALIERNATING CURRENT MOTORS.

APPLIdATIQK E'IIEED APR. 26, 1901.

10 MODEL. 2 SHEETS-$111521 UNITED STATES Patented June 23, 1903.

PATENT OFFICE.

PAUL JACQUES MATHURIN GIRAULT, OF PARIS, FRANCE.

SPECIFICATION forming part of Letters Patent No. 731,887, dated June 23,1903.

' Application filed April 26, 1901. Serial No. 57,625. (N0 mode To allwhom it may concern:

Be it known that 1, PAUL JACQUES MATHU- RIN GIRAULT, engineer, a citizenof the French Republic, residing at Paris, France, (whose post-officeaddress is 71 Rue Pamrmont, in the said city,) have invented certain newand useful Improvements in Methods of Controlling Alternating- CurrentMotors, of which the following is a specification.

Induction electric motors with revolving magnetic field and an armatureof low resistance have the disadvantage of absorbing heavy currents whentheir inducing-fields are switched in the circuit and of being uncertainin their starting unless special devices be resorted to. I obviate thisdisadvantage by introducing resistances of known value into thearmature-circuits and cutting them off gradually as the speed of themotor increases. I re duce the intensities of the current when inducing-fields are being switched in and in sure the starting, of themotors.

My said invention is based on the use of transformers with singlewindings, by means of which the apparent resistances of thearmature-circuit are caused to vary in a continuous manner. By apparentresistance of a circuit I mean the ratio of the electromotive forcegenerated in the said circuit to the efiective intensity of the currentfiowing through it. This circuit can contain ohmicresistanceself-induction capacity and can be in inductive relation with anothercircuit, or it can be in connection with part of itself, which parts areput into short circuit.

Figure 1 shows, as example, an application of my invention to athree-phase-current motor. A A A are the inducing-circuits of the motor;ct a (t the circuits of the armature; c 0 0 the single windings of thetransformers, the turns of which are connected,respectively, to thefixed contacts of a commutator, on which a three-armed handle cl d dbears. By shifting the handle a gradually-increasing number of thesections of the single windings are short-circuited with the resistancesff f of zero or finite value without these sections being able to beshort-circuited apart. After this operation the apparent resistance ofthe circuits a a a may be more diminished by short-circuitingsuccessively the resistancesff f and after the windings a a a by closingthe switches 6 6 It is obvious that one three-phase trans-- former onlymay be used instead of the three transformers of Fig. 1. The transformermay be of any convenient shape, (straight-line or annular shape.) Fig. 2shows, for instance, a transformer of another shape. In this figure Ihave only shown one of the circuits of the armature in order to simplifythe drawing. The circuit a is connected to the diametrically oppositepoints 9 and h of the single winding 0 of a cylindrical transformerhaving a series of channels. of any convenient shape parallel to theaxis for the reception of the winding 0. This winding is closed withinitself and like the windings of a con tinuous current machine. Thepoints of junction of the various individual sections of the winding 0are connected to a collector, as in the case of a continuous-currentarmature. On this collector bear two brushes m m, connected to eachother by a resistance the value of which is either zero or finite. It isclear that if the line mmjoining the brushes coincides with Us there isno current passing through the resistance f. The apparatus works thentoward the circuit a as a bobbin, having a very high self-induction. Thecurrent is then very weak and can be practically ignored. tacts aremoving in the direction of the arrow, the current passing throughf, andconsequently the currentpassing through g h, increases gradually invalue and reach both their maximum when the line m m coincides with theline g h. The intensity of the current in the circuit a may then beslightly increased, or rather the apparent resistance of this circuitmaybe reduced to its smallest value, by first short-circuiting theresistance f (iff has a finite value) and then short-circuiting thewinding of the transformer by means of the switch 0.

It is obvious that my invention may be used with the simple alternatingor polyphase current induction-motor with rotating field.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

1. A method for controlling alternating- As the traveling concurrentmotors with revolving magnetic field, the induced circuits of which areconnected with the terminals of a transformer having single windings,consisting of short-circuiting the sections of the Winding onresistances of a determined value.

2. A method for controlling alternatingcurrent motors with revolvingmagnetic field having their induced circuits connected with theterminals of a transformer with single windings consisting of dividingthe winding of the transformer into sections which are progressivelyshort-circuited on a resistance of a definite value.

5. A method for controlling alternatingcurrent motors with revolvingmagnetic field, the induced circuits of which are connected with theterminals of a transformer having single windings,consisting ofshort-circuiting the sections of the winding on resistances the value ofwhich is either zero or finite.

6. A method of starting and regulating the angular speed of motors withmagnetic rotating field the circuits of the armature of which areconnected to the terminals of transformers having single windings,consisting of short-circuiting a gradually-increasing number of sectionsof the single windings with resistances the value of which is eitherzero or finite, substantially as described.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

PAUL JACQUES MATIIURIN GIRAULT.

WVitnesses:

HENRY SOHWAB, EDWARD P. MAOLEAN.

